        body {
            background-image: url('/static/download.jpg');
            background-size: cover;
            background-repeat: no-repeat;
            background-position: center;
            height: 100vh;
            color: white;
            margin: 0;
            display: flex;
            justify-content: center;
            align-items: center;
            font-family: Arial, sans-serif;
        }
        .container {
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            text-align: center;
            max-width: 500px; /* 容器宽度 */
            padding: 60px; /* 内边距 */
            background-color: rgba(0, 0, 0, 0.4); /* 背景颜色 */
            border-radius: 10px;
            box-shadow: 0 6px 15px rgba(0, 0, 0, 0.1); /* 阴影效果 */
        }
        /* 返回按钮样式 */
        .back-button {
            position: absolute;
            top: 30px;
            left: 30px;
            font-size: 2em;
            color: white;
            text-decoration: none;
            padding: 15px;
            z-index: 1000;
        }
        .back-button:hover {
            color: lightgray;
        }
        .title {
            font-size: 2.5em; /* 标题字体 */
            font-weight: bold;
            margin-bottom: 40px; /* 标题底部间距 */
        }
        .form-group {
            width: 100%;
            margin-bottom: 20px; /* 输入框间距 */
            display: flex;
            justify-content: center;
        }
        .form-group input {
            width: 100%;
            max-width: 350px; /* 输入框最大宽度 */
            padding: 12px 24px; /* 内边距 */
            background-color: white;
            border: none;
            border-radius: 30px; /* 圆角效果 */
            color: black;
            text-align: center;
            font-size: 1.2em; /* 字体大小 */
        }
        .form-group input::placeholder {
            color: black;
        }
        /* 按钮组样式 */
        .btn-group-custom {
            display: flex;
            justify-content: center;
            align-items: center;
            width: 100%;
            max-width: 350px;
            margin-top: 30px;
        }

        /* 按钮的样式 */
        .btn-custom {
            flex: 0 0 auto;
            padding: 12px 0; /* 按钮内边距 */
            border-radius: 30px; /* 圆角 */
            background-color: white;
            color: black;
            font-size: 1.2em; /* 字体大小 */
            text-align: center;
            border: 2px solid white;
            cursor: pointer;
            text-decoration: none;
            width: 150px; /* 减小按钮宽度 */
        }
        .btn-custom:hover {
            background-color: #f0f0f0;
            color: black;
        }
        .flash-message {
            width: 100%;
            max-width: 350px;
            margin-top: 15px;
            margin-left: auto;
            margin-right: auto;
            text-align: center;
        }
        .text-link {
            color: white;
            text-decoration: none;
            margin-top: 30px; /* 增大间距 */
        }
        .text-link:hover {
            color: lightgray;
        }